Stuffed Frog

Auntie Muriel ... took another large gulp of champagne, belched, and then said [to Harry and Elphias], “There’s no need to look like a pair of stuffed frogs! Before he came so respected and respectable and all that tosh, there were some mighty funny rumors about Albus!” (DH8)

Definition

“Stuffed frog” is a term used to describe someone looking utterly bewildered, similar to the common Australian slang term “stunned mullet.”